This invention relates to a solid-state sliver sensor for a textile machine, such as a textile card. The sliver sensor may also find application in other machines which process textile strands, particularly in sliver form. The sliver sensor includes a power supply, diagnostic circuitry and amplifier on the unit itself, instead of at a central location fed by electric cable. The sliver sensor generates an output signal to servo-control the output weight of the sliver in an autoleveling system. The autoleveler also utilizes the output signal from the sliver sensor to immediately stop sliver output from the machine if a "choke" occurs, thus preventing damage to drafting rolls and similar components.
Other features, described and claimed below, provide enhanced utility, efficiency and precision in controlling output sliver weight.
U.S. Pat. No. 4,823,597 discloses a measuring device for measuring the unit weight of sliver as it passes through a trumpet. The trumpet includes a trumpet gauge plate for supporting the trumpet and a pair of weighted elements mounted on each side of the plate. The plate includes upper, lower and central portions wherein the lower portion includes an opening for supporting the trumpet and the central portion has a reduced cross section. A plurality of strain gauges for detecting deflections are mounted on front and rear surfaces of the central portions adjacent the lower portion and the weighted elements. The strain gauges are electrically connected in a modified Wheatstone Bridge configuration. Deflection sensing in strain gauges adjacent the weighted elements cancel out deflection sensing produced by external vibrations to produce an accurate measurement of the sliver weight.
U.S. Pat. No. 4,947,947 discloses a measuring device for measuring the unit weight of sliver as it passes through a trumpet. The device includes a trumpet gauge plate for supporting the trumpet and a vibration compensating element mounted on the plate. A plurality of strain gauges for detecting deflections are mounted on front and rear surfaces of a central portion of the plate adjacent a lower portion and the compensating element. The plate is mounted on support means, for example, a pair of spring supports, which allow the trumpet to move in response to an overload to eliminate damage to the plate, particularly its central portion where the strain gauges are mounted and to return to its normal position after the overload is gone. During normal operation, without an overload, deflection sensing produced by external vibrations cancel out to produce an accurate measurement of the sliver weight. During an overload the trumpet moves to a new position to avoid damage to the plate, and then returns after the overload is gone enabling the measuring operation to continue.